System of control



Jan. 2, 1923.

K. A. SIMMON ET AL.

SYSTEM OF CONTROL.

2 SlllETi-JHIU I.

FILED JUNE 9,1919.

INVENTORS Karl A.S/mmon fi arv-y 1?. Meyer.

ATTORNEY WITNESSES:

Jan. 2, 1923. 1,440,500. K. A. SIMMON ET AL.

SYSTEM OF CONTROL.

FILED JUNE 9, 1919. 2 suzrssnu 2.

Reverse 10/ P far-ward from o man/dost Rub/W Sol-vii: Broke My Brake mvgmoas lfar/ A S/mman. Hag/r9 R Meyef.

WITNESSES:

flaw

M AfTORNEY Patented Jan. 2, 1923.

UNITED STATES 1,440,500 Pfl'ENT OFFICE.

KARL A. SIMMON, or EDGEWOOD PARK, AND-HARRY R. MEYER, or wrLxiNsavne, PENNSYLVANIA, ASSIGNORS T WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A conronarron or PENNSYLVANIA.

SYSTEM OF CONTROL.

Application filed June 9, 1919. Serial No. 302,813.

T 0 all 10 7mm it may concern- Be it known that we KARL A. SIMMON, a citizen of the United etates, and a resident of Edgewood Park, in the county of Allegheny and State of Pennsylvania, and

- HARRY R. MEYER, a citizen of the United States, and a resident of \Vilkinsburg,1n the county of Allegheny and State of Pennsyl- Vania, have invented a new and useful 'Improvement in Systems of Control, of which the following is a specification.

Our invention relates to systems of control for dynamo-electric machines, and it has special relation to the use of foot-operated controllers for electric railway-motor systems.

One object of our invention is to provide a system of the above-indicated character wherein a multi-position foot-operated controller is employed for electrically governing the operating circuits of an electric motor and also brake-controlling means therefor.

Another object of our invention is to provide, in conjunction with a foot-operated controller for the purpose just set forth, a hand-operated multi-position controller for effecting predetermined initial re-arrangement of the machine circuits.

A further object of our invent-ion is to provide a foot-operated controller-for notonly governing the machine and the braking circuits but provided with positions for also controlling door-operating circuits for the vehicle.

Still another object of our invention is to provide means operating in conjunction with a foot-operated controller of the type under consideration for preventing the closure of 40 the motor circuits until the brake release operation has been effected, thereby preventing a jerky start of the vehicle and also eliminating the waste of power that necessarily occurs when the vehicle is started before the brakes have been fully released.

A further object of our invention is to provide a system that may be governed by a foot-operated member to readily efi'ect dynamic braking of the vehicle motor or motors under emergency conditions.

Other minor objects of our invention will become evident from the following detailed description, taken in conjunction with the accompanying drawings, wherein Figure is a diagrammatic view of the maln circuits of a system of control that is governed in accordance with our present invention; and I Fig. 2 is a diagrammatic view of an auxiliary control system organized and arranged in accordance with the principles of the present invention.

Referring to Fig. l of the drawings, the system here shown comprises suitable supply-circuit conductors such as Trolley and Ground; a plurality of electric motors respectively having commutator-type armatures A1 and A2 and field windings F1 and F2 of the familiar series type; a controller 1 having a main-circuit portion 2 and an auxiliarv-circuit section 3, the controller being actuated by means of an electricallycontrolled, fluid-pressure-operated mechan sm 4; an accelerating resistor 5, the activecircuit value of which may be varied by the controller 1; a line switch LS for connecting the motors to the Trolley; a limit switch or current relay 6 of a familiar type for effecting automatic operation of the motors in a manner to be set forth; and a reversing switch 7 for reversing the electrical relations of the corresponding armatures and field windings. The reversing switch 7 is here shown diagrammatically for the sake of simplicity, but it will be understood that the preferred reversing switch takes the form of the familiar electro-pneumaticallv operated drum controller with suitable coritact fingers.

The lnailncircuit portion 2 of the drum controller 1 comprises a contact segment 8 for engaging a plurality of control fingers that are suitably connected to various points of the accelerating resistor 5, and other contact segments 9, 10 and 11 that are employed for effecting series-parallel arrangement of the motor circuits.

The actuating mechanism 4 is of a familiar electrically-controlled, pneumatically-operated type comprising a pinion 15 which is mounted upon the operating shaft 16 of the controller 1 to mesh with a transversely movable rack member 17 the opposite ends of which constitute pistons 18 and 19 that travel within suitable operating cylinders 20 and 21. An inverted valve 22, that is normally open to admit fluid pressure from a supply pipe 23 to the operating cylinder 20, is provided with an actuating coil Off, whereby the valve may be closed. A standard valve 24 normally cuts off communication between a su 3131 I pi e and the ooer-' i i J. i

ating cylinder 21, which is normally placed in communication with the atmosphere. An actuating coil ()n for the valve 24: serves to effect the opening movement thereof. Any suitable source of fluid pressure (not shown), such as the usualair reservoir that carried upon electric railway vehicles, may be utilized to supply fluid pressure to the inlet pines and 2.

I The operation of the actuating mechanism 4. may bebrieily set forth as follows. 21y re son of the normally open position of the K v ;ed valve the pistons 18 and 19 are biased to the illustrated. position, correspending to the initial position c of the controller 1. Upon concurrent energization of the actuating coils Off and On, fluid pressure is exhausted from the cylinder 20 to the atmosphere through the valve22 and is admitted through the other valve 2 to the operating cylinder 21. In this way, the normal. unbalanced relation of fluid pressures in the actuating mechanism isreversed to cause a movement of the pistons 18 and 19. and, therefore, of the controller 1 toward the left through the successive positions or notches d to 70, inclusive.

To arrest such movement at any time, it is merely-necessary to de-energize the oil coil, whereupon balanced high-fluid-pre sure conditions obtain in the mechanism and a positive and reliable stoppage thereof is secured.

To produce a return movement of the ap paratus, the actuating coils OH? On are concurrently deenergized, whereby fluidpressure conditions in the mechanism revert to the original unbalanced state, and the de sired backward movement is effected.

inasmuch as the particular main-circuit or. iections employed are not material to our present invention, it is not deemed necessary to trace, in detail, the series-paral cl circuits that are formed by movement of the controller 1 through its successive positions. It will be sullicientto state that position 7 corresponds to full series relation of the motors and position to full parallel relation thereof, transition of the motors being effected between position f and position i by means of the familiar shunting type of transition.

Referring to Fig. 2, the auxiliary system here shown comprises, in addition to the auxiliarycircuit portion Z of the controller 1 and the actuating coils for the fluid-pres sure mechanism l-and the line switch LS, a plurality of other actuating coils that are designated by descriptive legends such Brake release and. Door-opening, together with hand-operated selective switch 29, a foot-operated controller 30, a pneumatic relay 31, a door opening push-button i land a battery B, or other suitable source of energy, for the various illustrated actuating coils.

The selective switch'29 is provided with a handle 26 of a familiar type and is placed in a position corresponding to that of the customarily employed master controller. The selective switch may thus be readily 7 reached. by the motorman in either standing or a sitting position, for the purpose of effecting either forward or reverse operation of the motors in either or parallel relation. The illustrated. right-nand side of the controller corresponds to forwa 'd operation and positions 8 and f7 correspoiiul to series and parallel relation of the motors, respectively. The reverse sideof the selec tive switch is provided with correspondi positions 8 and f).

The foot-operated controller is located upon the platform floor ofthe vehicle and is provided with a pedal or foot-lever 9/2' for actuating the controller from the illustrated emergency brake position through the other positions designated as ice "tier 1 brake, Lap and pedal removal, Brake release, and coast and Power on. The preferred construction of thefoot-operated controller, including means for biasing); it to the illustrated emergency brake ymsition, is fully set forth in our copending applicatiom Serial No. 283,4:"2'4l, filed lvlarch 19, 1919.

lt will be understood that an well-known type of braking system may be employed in the present instance to be governed by the foot-operated controller 30 jointly with the control of the motor circuits, but we prefer to employ the familiar air-brake system, electrically controlling it through the agency of three valves, the actu for which are respectively marked release and Brake application", valves being of the standard type, such as 24 shown in Fig. 1, and emergency brake. the associated valve being of the inverted type, asv notedin 52, such as the valve 22 illustrated in l 1. Thus, the en1ergency brake valve is normally open, that is to say, an emergency braking ZLPPllCfitlOll is made whenever'the foot-operated controller 30 occupies its biased illustrated position. On the other hand, the bralre-release and the brake application valves are actuated to perform the corresponding operation only when the foot-operated controller 30 occupies certain other positions, as subsequently described in. detail.

The door-opening and the door-closing apparatus is also preferably of a fmiliar electro-pneu natic type, embodying; sta; c valves, 24:, rvhich are alternativ tuated to effect the desired operation of the vehicle doors. la the present (11," l

doors are opened through the agency of the push-button 14 and are closed in the brake-release position of the foot-operated controller 30.

The pneumatic relay 31 is employed for the purpose of ensuring that the vehicle brakes are released before the motor circuits can be closed. The relav is shown as comprising an operating cylinder 28, which is placed in communication with the brake cylinder of the vehicle by means of a pipe 28, together with a flexible diaphragm 32 that is biased to the illustrated'lower position by means of a helical spring within the cylinder 28. The spring 33 acts in opposition to fluid pressure that is admitted to the lower end of the cylinder 28 whenever fluid pressure is present in the brake cylinder or, in other words, whenever an application of the brakes, either service or emergencv. is being made.

l Vhenever the brakes are released, as evidenced by the exhaust of fluid pressure from the brake cylinder, a contact segment or electrical interlock 34L occupies the illustrated closed-circuit position to permit energization of the actuatin coil for the line switch LS, as hereinafter more fully set forth. In this Way, complete release of the vehicle brakes is ensured before the vehicle may be operated, the advantages of which arrangement have already been set forth.

Assuming that it is desired to effect acceleration of the motors when the various pieces of apparatus occupy the illustrated normal positions, the selective switch 29 is first actuated to the desired position.in the first place, to produce the proper direction of operation, and, secondly, to predetermine the final motor speed to be automatically attained, as about to be described. In, other words, .in congested. districts, it may be well to actuate the selective switch to series position 8, so that the motors will not be automatically connected in the higher-speed parallel relation. whereas. in thinly populated districts, the selective switch 2.) may be initially thrown to its parallel position 79, and automatic accelera tion of the motors to full speed may then be effected.

Such actuation of the selective switch 29 to any desired position does not complete any controlling circuits until the foot-operated controller has been actuated. In this way, the motorman may place the selective switch 29 in the desired position at the beginning of a trip and no further attention need be paid thereto until it is desired. to change the setting thereof, full control of the vehicle being generally secured by means of the foot-operated controller 3-30 alone.

Assuming that the foot-operated controller 30 is actuated from its illustrated biased position, designated as Emergency brake, to the other extreme position Power on, a circuit is first completed, as the controller passes through its service brake position, from the positive terminal of the battery B, through conductor train-line conductor 36, conductor 37, control finger 38, contact segment 39, conductor e0, contact segment 41 and control finger 42 of the foot-operated controller, whence circuit is continued through conductor 43, trainline conductor 44, conductor 15, actuating coil of the Emergency Brake valve, conductor 46, traiirline conductor 47 and conductor 48 to the negative battery terminal. In this way, the emergency brake valve, which. as previousl stated, is of the inverted or normally open type, is closed to discontinue the emergency-braking operation.

The service brake application is also made under normal conditions, that is to say, whenever the vehicle is stopped and the foot-operated controller occupies its illustrated position, by reason of the energization of control finger 9i from the contact segment 41, whence circuit is continued through conductor 95, train-line conductor 96, conductor 97, actuating coil of the brake-application valve, and thence to the negative battery terminal, already described. The circuit just traced is interrupted. as soon as the foot-controller reaches its position Lap, and pedal removal by reason of the disengagement of the control finger 9% from the contact segment 41. Thus, both the emergency and the servicebrake-application valves are operated to prevent further brake application as soon as the foot-operated controller 30 reaches its lap position, thereby corresponding to the familiar lap position of the engineeids valve for straight air-brake svsten'isl in the brake release, and co position of the controller 30. a new circuit is continued from the contact sgment 39 through control Ii l9, cmnlm or 5U, train-line condinxtor i emnluctor 52, and the actual:- ing coil. for the bralaw-release valve. In this way, the brake-release operation is performed, thus effecting exhaust of fluid pressure from the brake cylinder to remove the brake-shoe from the vehicle wheels and also to permit actuation of the pneumatic relay 31 to the illustrated closelcircuit position.

Another circuit is completed, in the brakerelease position of the foot-operated controller 30, from the contact segment 39 through control finger 53, conductor 54. train-line conductor conductor 56 and the actuating coil of the door-closing valve. Thus, the vehicle doors are closed without requiring any manna. manipulation upon the part of the niotm'man, and such closure 1.;

is necessary to permit operation of the vehicle, by reason or the inclusion or the familiar door interlocks in the governing circuit or the line switch, as about to be described.

W hen the footoperated controller 30 has reached its final position Power on, a new circuit is completed from the contact segment 39 through control finger 57, conductor 58, train-line conductor 59, conductor 60, control fingers 61 and 652, which are bridged by contact egment 6:2, in series position 8, for example, of the selective switch 29, whence circuit is continued through conductor-s63 and 64, contact segment (55, of a ilfamiliar form, that is placed upon the maincircuit reversing switch 7, conductor 66, the above-mentioned door interlocks, interlock 3. oi? the pneumatic relay 31 in its closed position, conductor 67, the actuating coil for the line switch LS, conductor 68, contact segment Drum-0, (whereby the circuit being traced can be completed only when the controller 1 occupies its initial position (2), circuit being completed through conductor 69 to the negative conductor L6. The line switch LS isthus closed to complete the initial connection of the motors through the accelerating resistor 5 across the supply circuit, as will be understood without detailed description.

The closure of the line switch causes an interlock LEE-in of the usual type to bridge the contact segment Drum-c, thus ensuring the continued closure of the line switch when the drum controller 1 leaves its initial position, as about to be set forth.

The actuating coil On for the operating mechanism 4 is also energized under initial operating conditions, that is, as soon as the foot-operated controller 30 reaches its power on position, by reason of the permanent connection oi? the coil between the positively-energized conduct-0r G6 and negatire conductor 69.

firs soon as the :loot-operated controller 30 occupies its power on position, a further circuit completed from the thereby energir icd conic 2t segment 62 oi the selective switch 29, through control linger 70, conductor 7i, train-line conductor 72, conductor 7 8, control fingers 7a and 75, which are bridged by contact segment 7 6, comprising the auxiliary-circuit section 3 of the controller 1, whence circuit is continued through conductor 77, contact disk 7 8 of the limit switch or current relay 6, whenever occupying its lower position, and actuating coil (lit of the mechanism 4: to the negative conductor 46.

Since both the on and the oil coils for the actuating mechanism l are thus concurrently energized whenever the limit switch (3 occupies its low-current position, forward umvement oi? the controller 1 occurs in a step-by-step manner responsive to the movements of the limit switch, as will be understood by those skilled in th art.

To prevent the controller 1 from, sticking in, a position intermediate the illustrated notches, the contact segment 76 is provided with a plurality of depending tongues that engage a control finger 79 be tween the successive pairs of notches, wher by energy is led directly through conductor 80 to the actuating coil Oil. The contact disk 7 8 of the limit switch 6 is thus shortcircuited between. controller notches to insure the continuous movement of the controller from notchto notch under the control of the limit switch.

in case the selective switch 2-9 occupies its position a, as in the assumed. case, the main controller 1 stops in its full-series position f.

However, the selective switch 29 has initially been moved to its position p or is moved to that position when the motors have attained their full series relation, provided the motorm an maintains the foot-- operated controller 3 in its power on position, further step-by-step movement of the main controller 1 to its final position 70, corresponding to full-parallel relation of the motors, automatically effected under the control of the limit switch 6.

It, at any time, an emergency stop of the vehicle is desired to prevent accident, or for any other reason, the motorman merely removes his foot from the pedal 27, and the tootoperated controller 80 returns to its biased illustrated position to effect the emergency braking operation, by reason of the disengagement of the control finger 42 from the contact segment ll.

However, to eiiect a service-brake application, the motorman operates the pedal 527 to return the controller 30 to its service-brake pos ion, whereby the previously-traced circuit through the brakeapplication coil is completed to produce the dc ired. service brake operation, By lating the controller 3%) between the servic bralre and the lap position, the i'ai an -braking l'otu'rda tion of the vehicle is secured l' i henever the foot-operated controller 30 occupies any one of the positions Lap, Service-brake or n lumergency brake, any one of which may be occupied when the vehicle comes to rest, the vehicle doors: may be opened by depressing the push-button 14. Under such conditions, a circuit is completed from the contact segment ll oi the iootoperated controller through control finger S6, conductor 87, train-line conductor 88, conductor and 91, which are bridged by movable contact member 90 of the push button 1%- circuit is continued whence through train-line conductor 92, conductor 9. actuating coil of the door-opening valve, and thence, through the .ne

n ti ve con d u ctor 116, to the battery B. Thus, the vehicle doors are opened whenever the push-button 14 is depressed and the foot-operated controller 30 concurrently occupies a suitable position.

To effect reverse operation of the vehicle to make the return trip, for example, the foot-operated controller 30 is locked in its lap position in the manner set forth in our above -identified copending application, whereby the brake applications are prevented, and the pedal 27 may then be removed to be placed upon the corresponding controller at the other end of the vehicle.

IIowever, if it is desired to reverse the operation of the car from the operating end, at that time, the selective switch 29 is actuated to its position 8, for example, after the vehicle has come to rest. Under such conditions, a circuit is established, as soon as the foot-operated controller has been returned toits power on position, from the posi tively energized control finger 61 through contact segment 99 and control finger 100, whence circuit iscontinued through conductor 101, train-line conductor 102, conductor 103, contact segment 104 of the main-circuit reversing switch 7, conductor 105, and the actuating coil Rev. of the reversing switch to negative conductor 46. In this way, the reverser which, as previously stated, is preferably of the familiar electrically-controlled pneumatiCally-actuated type, is thrown to its reverse position-before movement of the vehicle may be obtained.

As soon as the reversing switch 7 occupies its reverse position, the circuit of the conductor'103 is transferred through contact segment 104 to conductor 66, whereby the line switch LS may be closed and the operation of the vehicle may be effected, as already set forth.

A further advantage of the system illustrated resides in the fact that, under emergency conditions, such as failure of the airbrake system or opening of the line switch under operating conditions,.for any reason, dynamic braking of the motoys to effectively retard the vehicle motion may be readily effected.

Such braking action is possible because the main controller 1 may be actuated to its parallel positions independently of the condition of the line switch IS, since both the on and the off coils for the operating mechanism 4: are energized directly through the foot-operated controller 80 and the main controller 1 without any interlocking with theline switch.

Consequently, under the above-noted emergency conditions, the selective switch 29 may be thrown to the position corresponding to reverse operation of the motors, while the foot-operated controller is maintained in, or actuated to its power on position. Under such conditions, the main controller 1 is rapidly actuated to its linal parallel position 70, since the limit switch (3 remains in its lower or circuit-closing position. As soon as the first parallel position 7t is reached, a local circuit is closed through the two motor a rmatures and field windings, the latter being reversed by reason of the above-men interlock Drum-sin the circuit of that coil. I

In this way, an emergency-braking action is made available without requiring any additional or special circuits therefor, and such action may be safely employed by reason of the fact that it is impossible, under such conditions, to reconnect the motors to the supply circuit.

lVe do not wish to be restricted to the specific structural details, circuit connections or arrangement of parts herein set forth, as various modifications thereof may be made without departing from the spirit and scope of our invention. We desire, therefore, that only such limitations shall be imposed as are indicated in the appended claims.

\Ve claim as our invention:

1. In a system of control, the combination with a dynamo-electric machine, and brakecontrolling means therefonof a multi-position foot-operated controller for electrically governing said machine and said brakecontrolling means.

2. In a system of control, the combination with a. plurality of governing circuits and brake-controlling means, of a foot-operated controller for electrically governing said circuits and said brake-controlling means in a predetermined step'by-step manner.

3. Ina system f control, the combination with a dynamo-electric machine and electri-. cally governed brake controlling means therefor, of a foot-operated electrical controller having certain positions respectively corresponding to certain operating conditions of said machine and of said brake-controlling means and having other positions corresponding to modified machine conditions and brake applications.

4. In a system of control, the combination with a dynamo-electric machine and electrically governed brake controlling means therefor, of a footroperated electrical controller having its extreme positions respectively corresponding to certain operating conditions of said machine :mdof saidbrakecontrolling means and having intermediate positions corresponding to modified machine conditions and brake applications.

' 5. In a system of control, the combination with a dynamo-electric machine and brakecontrolling means therefor, of a foot-operated controller having a normal position for effecting emergency braking'operation of said brake-controlling means, an adjacent position for effecting service braking op eration of said means, and other successive positions for effecting release operation of said means and operating connections of said machine.

6. In a system of control, the combination with a dynamo electric machine and brakecontrolling means therefor, of a multi-position foot-operated controller for electrically governing said machine and said brake-controlling means, and h and-operated multi-po sition means for elfectingrearrangement of the machine circuits.

7. In a systemof control, the combination with a dynamo-electricmachine and brakecontrolling means therefor, of multi-position footoperated controller, for electrically governing said machine and said brake-controlling means, and a hand-operated controller for effecting reversal of the operation of said machine.

8. In a system of control, the combina tion with a plurality of dynamo-electric machines and brake-controlling means therefor, of a multirpositiorl foot-opented controller for electrically governing said machine and said brake-controlling means, and a handoperated controller for effecting adjustment of the connections of the machines for series or parallel relation thereof.

9. In a system of control, the combination with a plurality of dynamo-electro machines and hralte-oontrolling means therefor, of a multi-position foot-operated controller for electrically governing said machine and said brake-controlling means, and a hand-operated controller for effecting reversal and series-parallel operation of said machines.

10. In a system of control, thecombination with a plurality of dynamo-electric machines and hrake-controlling means therefor, of a multi'position controller for elec trically governing said machine and said hrake-oontrolling means, and a second controller for effecting adjustment of the connections of the machine for series or allel relation thereof.

11. In a sysJem of control, the combination with a dy11an1o-electric machine and brake-controlling means therefor, of a handoperated controller for adjusting certain of the machine circuits, and a foot-operated controller for electrically governing said machine and said brake-controlling means and for rendering the circuits of said handopelatedccntroller active par-- 115. In a system of control, the collllllllih tion 'Wltll a dynamo-electric machine and brake-controlling means therefor, of a hand operated controller for adjusting certain of the machine circuits, a source of energy, and a foot-operated controller interposed between said source and said hand-operated controller for normally preventing the energization thereof.

13. In a system of vehicle control, the combination with a dynamo-electric machine, of a vehicle-door-controlling circuit, and a multi-position foot-operated controller for governing both said machine and said door-controlling circuit.

14:. In a system of vehicle control, the combination With a dynamo-electric machine and brake-controlling means therefor, of a vehicledoor-controlling circuit, and a multi-position foot-operated controller for governing said machine, said brake-controlling means and said door-controlling circuit. I

15. In a system of control, the combina' tion with a dynamo-electric machine and brake-controlling means therefor, of a door closing circuit, and a foot-operated controller having a normal position for effecting emergency braking operation of said brakecontrolling means, an adjacent position for effecting service braking operation of said means, and other successive positions for concurrently effecting release opera tion of said means and rendering said door closing circuit active, and for effecting op erating connections of said machine.

16. In a system of control, the combination with a dynamo-electric machine and brake-controlling means therefor, of a multi-position controller for governing said machine and said brake-controlling means, and means for preventing the operation of said machine unless the brake-release operation has been effected.

17. In a system of control, the combination with a dynamo-electric machine and brake-controlling means therefor, of afootoperated controller having certain positions respectively corresponding to certain oper ating conditions of said machine and of saidbrakecontrolling means and having other positions corresponding to modified machine conditions and brake applications, and means for ensuring that the brakerelease operation has been efi'ected before rendering the machmegoverninge circuits active.

18. In a system of control, thecombination with adynamo-electric machine and brake-controlling means therefor, of a foot operated controller having. a normal posi tion for elfecting emergency braking operation of said brake-controlling means, an adjacent position for effecting service braking operation of said means, and other successive positions for efi'ecting release operation of said means and operating connections of said machine, and means responsive to the brake-release operation for effecting the initial closure of the machine clrcuits.

19. In a system of control, the combination with a plurality of dynamo-electric machines, of control means for connecting said machines in series and in parallel relation, and means comprising a foot-operated member for governing said control means to connect said machines in parallel relation to effect dynamic braking under conditions of de-energization of the machines.

20. In a system of control, the combination with a supply circuit and a dynamoelectric machine, of means for connecting said machine to the supply circuit under opcrating conditions, and means comprising a foot-operated member for effecting dynamic braking of said machine when said connecting means is open.

21. In a system of control, the combination with a dynamo-electric machine, of control means for normally efi'ecting acceleration of said machine, and means comprising a foot-operated member and a hand-operated member for governing said control means and said machine to effect dynamic braking thereof under predetermined. oper ating conditions.

22. In a system of control, the combination with a plurality of dynamo-electric machines, of a controller for connecting said machines in series and in parallel. relation, electrical means for effecting actuation of said controller, means for reversing said machines, and means comprising a foot-operated member for energizing said electrical means to effect connection of the reversed machines in parallel relation and dynamic braking thereof under predetermined operating conditions.

23. In a system of control, the combination with a dynamo-electric machine, of a controller for normally effecting acceleration of said machine, means for effecting actuation of said controller, hand-operated means for reversing said machine, and means comprising a foot-operated member for governing said actuating means to effect dynamic braking of the reversed machine under predetermined operating conditions.

In testimony whereof, We have hereunto subscribed our names this 26th day of May, 1919.

KARL A. SIMMON.

HARRY R. MEYER. 

